Stabilized yarn



United States Patent 3,h82,110 sTAliillllZE i) YARN Robert C.Harrington, In, and James L. Smith, Kmgsport,

Tenn, assignors to Eastman Kodak Company, Rochestel, N.Y., a corporationof New Jersey No Drawing. Filed Oct. 25, 1960, Ser. No. 64,694 7(Ilairns. (Cl. 106-194) This invention relates to a composition ofmatter, especially a cellulose ester containing composition whlchcomposition exhibits stability to actinic radiation. More particularly,this invention relates to dull and semi-dull cellulose ester filamentswhich are relatively highly stable toward photodegradation.

It is already well known in the industry to prepare spinning solutionsof spinnable materials such as cellulose esters dissolved in a solvent.It is further known to extrude such spinning solutions throughspinnerettes to form filaments therefrom by the elimination of thesolvent from the extruded materials. In the manufacture of the so-calleddull or semi-dull or delustered fibers, it is customary to include apigment in the spinning solution for obtaining the dull or delusteredeffect. As is well known, titanium dioxide in finely divided form is afrequently used delustering pigment.

Studies have shown that scission of the polymer chain of the fiberforming material by light is catalyzed by titanium dioxide. Therefore,photodegradation of dull or semi-dull or the like delustered fibers ismore severe than for the so-called bright yarns which do not include orinclude a lesser amount of such pigments as titanium dioxide. In orderto retard such type photodegradation especially in the dull ordelustered fibers as just referred to, it has already been proposed toincorporate ultraviolet light absorbing materials and antioxidants intothe spinning compositions or onto the surface of the fibers or fabricswoven therefrom. Presumably the functioning of prior additives has beenpostulated on the theory that peroxides are formed in the fibers throughthe absorption of ultraviolet radiations. Thus the fiber material mightbe protected if the rays or radiation can be absorbed preferentially bysome compound incorporated in the fiber or if the peroxides once formedare quickly taken care of by some agent such as an antioxidant in thefiber.

While prior .art methods of stabilization have received some favorableacceptance in the industry, it is apparent that the development offurther more simplified or different procedures for stabilizingcellulose ester compositions represents a highly desirable result. Afterextended o investigation we have found a procedure of stabilizing and astabilizing agent which appears not only to very efiiciently function,but to function by a mechanism different from the prior art stabilizersand in a manner, the principle of which is presently unknown to us.

This invention has for one object to provide compositions of matterespecially compositions containing a substantial content of cellulose.acetate which compositions exhibit relatively good stability towardactinic radiations. A particular object is to provide a celluloseacetate spinning solution which is relatively highly stable to actinicradiation and which may be spun into filaments wherein the resultantfilaments not only possess their original properties, but have betterstability to photodegradation. A further object is to provide celluloseacetate fibers so stabilized that they are not substantiallydeleteriously affected with respect to strength, elongation or color. Astill further object is to provide procedure for incorporating certainnovel additives into cellulose ester spinning solutions and the spinningof fibers from such solutions. Other objects will appear hereinafter.

In the broader aspects of the present invention we have found thatcompositions of matter and more par ticularly exemplified by spinningsolutions which ma: have added thereto a small portion of zinc acetylace tonate with the beneficial effect that such combinatioi and theextruded products resulting therefrom have decreased rate ofphotodegradation. Zinc acetyl ace tonate is a compound having thefollowing type formula CH2 ZI1(O(|.L1CH2-(I|]CH3)2 In general we havefound that a concentration as lov as 0.1% based on the weight of thecomposition 0 matter will give a beneficial effect. Usually we WOlJltnot use more than 1.5% by Weight. In the instance 0 cellulose esterspinning solutions we have found that concentration between 0.4% and0.7% based on thl cellulose ester weight is quite satisfactory. We havlfound that our zinc acetyl acetonate additive is particu larly effectivein cellulose ester spinning solutions whicl contain titanium dioxidedelustering or dulling agents.

In further detail, zinc acetyl acetonate may be preparer by thefollowing procedure. Four hundred ml. of ab solute ethyl alcohol wereplaced in a flask fitted with stirrer, condenser and thermometer. Thealcohol wa protected from atmospheric moisture by means of a cal ciumchloride tube. One mole, 23 grams, of sodium was added in small pieces.After all the sodium ha reacted, one mole of 2,4-pentanedione (acetylacetone: was slowly added. The solution was maintained for 34 minutes ata temperature sufiicient to cause refluxing Then /2 mole (68.2 grams) ofanhydrous zinc chloridl dissolved in absolute alcohol was added over aZO-minutI period and the mixture was maintained at refluxing temperature for an hour. The mixture was filtered whil. hot to removeprecipitated sodium chloride. Zinc acety acetonate crystallized from thefiltrate on cooling. I was collected by filtration and recrystallizedfrom ethy alcohol.

While we prefer the foregoing type of method for pro ducing the zincacetyl acetonate, the exact source of thi additive or its method ofmanufacture is not a limitatioi on the present invention. A suitablequality zinc acety acetonate is obtained and then ground in the presence0 the type of solvent that is to be used in dissolving th solid materialfrom which the fibers are to be produced For example, in the instance ofcellulose acetate, aceton is the type of solvent usually used fordissolving th cellulose acetate. Therefore, the zinc acetyl acetonatwould be ground in the presence of acetone. A spinnin, solution may bemade in the usual way from the filamen forming material, titaniumdioxide or comparable de lusterant, coloring material or the liketogether wit] 0.1% to 1.5% of the zinc acetyl acetonate of the preseninvention. Such spinning solutions may then be spun int filaments byconventional procedures such as dry spin ning, wet spinning, meltspinning or the like to produc filaments which exhibit greaterresistance to .actinic radia tions either in the filament form or in theform 0 products such as fabrics.

A further understanding of our invention may be ha from a considerationof the following examples whic'. are set forth for illustrating certainpreferred embodi ments.

Example I In accordance with this example the white fine acety acetonatepowder-like solid was ground in the presenc of acetone. This mixture wasadded to a 27% solutio: of secondary cellulose acetate in acetone inwhich 1.4% based on the acetate weight, of titanium dioxide ha beensuspended. The concentration of zinc acetyl ace tonate was 0.5% based onthe weight of cellulose ace :ate. The solution was dry spun in aconventional manner by extruding it through small orifices into a drying:hamber to remove the solvent. Continuous filament yarn of 150 denierwith 38 filaments prepared as described above was used as filling in a75-denier bright lcetate Warp. A satin Weave was used wherein the yarnihowing on the dull side of the fabric commonly referred as the back,was about 80% cellulose acetate contain- .ng 0.5% zinc acetyl acetonate.The fabric was exposed ;0 light rich in ultraviolet in a Fade-Ometer, aninstrunent utilizing a carbon arc. The dull side of the fabric wasturned toward the light. A control fabric, identical :0 the onedescribed above except that the 150 denier iull yarn contained no zincacetyl acetonate, was exposed .0 light in the same manner.

Strips of each fabric were exposed in a Fade-Ometer for 400 and 600hours. Before exposure and after each .ime period the samples weretested. The forces were neasured which were necessary to pull apart, ina longi- .udinal direction, strips one inch wide and three inches ong.The strips had been cut from the fabric samples that the filling wasrunning longitudinally and thus the )ulling was done against the fibersin the filling. The ibers containing zinc acetyl acetonate retained amuch arger portion of their original strength and lost strength essquickly than the control samples. After 400 hours ;he control sample hadlost 57% of its original strength vhile the one containing zinc acetylacetonate had lost 52%. After 600 hours, the sample containing the zinc:ompound was 62% stronger than the control.

Example 11 Yarn containing 0.1% zinc acetyl acetonate was pre- :iaredand tested in an analogous manner to the yarn in Example 1. After 600hours in a Fade-Ometer the fabric was 38% stronger than a controlfabric.

Example 111 A fiber forming spinning solution consisting of acetonelOlVGIlt, cellulose acetate (39.3% acetyl) at a concentra- ;ion of 27%,and zinc acetyl acetonate at a concentration )f 0.5% based upon theacetate weight was dry spun in 1 conventional manner. The fibers of 4denier per filanent were wound on wire frames and exposed in a Fade-Dmeter for 400 hours. Control fibers containing no zinc rcetyl acetonatewere prepared and tested in the same nanner. The stabilized fibers lostonly 7.1% of their itrength while the control fibers lost 29%. In otherwords the stabilized fibers were losing strength at only he rate of thecontrol fibers. After the same exposure aeriod, the percent loss in theelongation of the control ibers was 60 while the stabilized fiber lostonly 0.55 per- :ent of its original elongation. It should be noted, asilustrated by this example, that zinc acetyl acetonate also ;erves as astabilizer in the absence of titanium dioxide.

Example IV Two films of cellulose acetate butyrate, 13% acetyl and 37%butyryl, one containing 0.7% zinc acetyl ace- :onate and the other nostabilizer were cast from acetone :olutions. The films, 0.05 inch thickwere exposed to iltraviolet light in a Fade ometer for 400 hours. Thentrinsic viscosities of the polymers were determined both )efore andafter exposure. The stabilized polymer lost nly 2 percent of itsoriginal intrinsic viscosity while the :ontrol which contained no zincacetyl acetonate lost 18 Jercent. Loss in intrinsic viscosity isindicative of a coresponding loss in strength.

Example V Example IV was repeated except that cellulose triaceate films,one with 0.7% zinc acetylacetonate and the ather without the stabilizer,were cast from a solvent con- ;isting of nine parts of methylenechloride and one part of methanol by weight. After 400 hours in theFade-Ometer the stabilized film had lost 6% of its original intrinsicviscosity while the control had lost 20%.

It can be seen from the foregoing description that we have provided anumber of new compositions of matter, particularly in the form ofspinning solutions.

Such spinning solutions enable the production of filamentary and fabricproducts that are more resistant to actinic radiation than comparableproducts heretofore available. While our invention is particularlyapplicable to cellulose acetate compositions in the form of acetonespinning solutions made therefrom, certain other benefits of ourinvention may be had in combination with other types of fiber and filmforming materials. Illustrations of these variations are as follows:cellulose triacetate, cellulose tripropionate, cellulose acetatebutyrate and mixtures of cellulosic esters with other polymers.

Although we prefer to use acetone as the solvent for the fiber formingmaterials and for grinding the additive, since it is a well-knownreadily available commercial solvent, other solvents and solventcombinations may be used illustrated by the following: chlorinatedhydrocarbons such as methylene chloride and tetrachloroethane,chlorinated hydrocarbons mixed with low molecular weight alcohols suchas that illustrated in Example V, and lower N,N dialkyl .alkanamidessuch as dimethyl formamide.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention as described hereinabove and as defined in the appendedclaims.

We claim:

1. As a new composition of matter adapted for spinning, a solutionconsisting principally of a lower cellulose ester, a solvent for saidlower cellulose ester, and 0.1 to 1.5% of zinc acetyl acetonate based onthe weight of said lower cellulose ester.

2. A composition according to claim 1 wherein the cellulose esterconsists essentially of cellulose acetate and 0.25 to 5% by weight ofsaid cellulose ester of titanium dioxide.

3. As a new article of manufacture, a fabric comprising a lowercellulose ester, 0.1 to 1.5% zinc acetyl acetonate based on the weightof said lower cellulose ester, and 0.2 to 5% titanium dioxide based onthe weight of said lower cellulose ester.

4. A product in accordance with claim 3 wherein the lower celluloseester consists essentially of cellulose acetate.

5. As a new article of manufacture, a fabric which consists essentiallyof lower cellulose ester fibers containing 0.1 to 1.5% by weight of zincacetyl acetonate whereby the fibers exhibit enhanced resistance tophotodegradation.

6. A product in accordance with claim 5 wherein the lower celluloseester consists essentially of cellulose acetate.

7. The method of preparing filaments of increased resistance to actinicradiation which comprises dry spinning a solution of cellulose acetate,0.1 to 1.5% zinc acetyl acetonate based on the weight of said celluloseacetate and 0.25 to 5% titanium dioxide based on the weight of saidcellulose acetate.

References Cited in the file of this patent UNITED STATES PATENTS2,615,860 Burgess Oct. 28, 1952 2,819,978 Long et al Ian. 14, 1958FOREIGN PATENTS 830,475 France Aug. 1, 1938

1. AS A NEW COMPOSITION OF MATTER ADAPTED FOR SPINNING, A SOLUTIONCONSISTING PRINCIPALLY OF A LOWER CELLULOSE ESTER, A SOLVENT FOR SAIDLOWER CELLULOSE ESTER, AND 0.1 TO 1.5% OF ZINC ACETYL ACETONATE BASED ONTHE WEIGHT OF SAID LOWER CELLULOSE ESTER.